tenacious, stubborn, pertinacious, and obstinate [pertinacious = perversely persistent]
tendency, drift, scope, and disposition
tests, trials, temptations, and toils
theatrical, ceremonious, meretricious, and ostentatious [meretricious = plausible but insincere]
theory, assumption, speculation, and conjecture
think, reflect, weigh, and ponder
tortuous, twisted, sinuous, and circuitous
tractable, gentle, pliant, and submissive
traditional, uncertain, legendary, and unverified
traffic, trade, commerce, and intercourse